Rotating piston machine

ABSTRACT

The invention pertains to a rotary piston machine in which a rotor rotates in an enclosure and radially movable slides in the rotor form chambers of varying volume between the enclosure and the rotor, wherein an even number of slides is provided and mutually opposing slides are joined together into a rigid unit.The invention is characterized in that the rotor is arranged eccentrically in the enclosure, in that, in polar coordinates with the center in the rotor shaft, the inside wall of the enclosure (32) satisfies the following equation:where:b is the shortest distance between the rotor shaft and the enclosure wall in the south pole (S),a is given by the formulawhere:d is the length of slides and 1 is given by the formula

BACKGROUND OF THE INVENTION

The invention pertains to a rotary piston machine in which a rotorrotates in an enclosure and radially movable slides in the rotor formchambers of varying volume between the enclosure and the rotor, whereinan even number of slides are provided and mutually opposing slides arejoined together into a rigid unit.

Such a rotary piston machine is known from GB 430 715 B. Here theenclosure has the form of a Reuleaux triangle and the rotor is arrangedcentrally in the triangle. The advantage of such an arrangement over andabove the use of one-sided spring-loaded slides is that in the rotationof the rotor, the enclosure wall need overcome only the inertial mass ofthe slide to move it back and forth while the centrifugal accelerationis at least essentially cancelled by the joining of the diametricallyopposing slides, and spring forces that must always be provided forindividual slides in order to press them against the wall in the firstplace can be completely eliminated.

Thus, a rotary piston machine of the type mentioned initially issubjected to considerably reduced wear in comparison to rotary pistonmachines with individually movable slides.

As more distant prior art pertaining to these other rotary pistonmachines that one can refer to, for instance, to DD-33 914 A in whichthe enclosure has a circular cross section, and the rotor arrangedeccentrically in the enclosure likewise has an essentially circularcross section but with recesses bounded in cross section by a circulararc being cut out of the rotor in order to increase the size of thechambers formed. The (four) slides are each pressed outward from therotor by springs against the enclosure wall, which, together with thecentrifugal acceleration, leads to large contact pressures and highwear.

Despite its advantages over and above DD-A, it is disadvantageous in therotary piston machine known from GB-B in that, because of thecompulsorily prescribed shape of a Reuleaux triangle, the formation ofthree enclosure pockets is inevitable during rotation, each pocketforming by a slide an initially expanding and then again shrinkingchamber between the slides. In internal combustion engines, forinstance, this necessarily leads to the formation of 6-stroke systemswith intervening cooling sections. Another disadvantage caused by thisis that each slide is pushed radially back and forth three times duringa rotation which in turn in the course of a rotation leads to relativelyhigh acceleration peaks.

SUMMARY OF THE INVENTION

The invention intends to create a remedy for this, and to specify arotary piston machine of the type defined initially in which each slideis pushed back and forth only once in a [single] rotation of the rotor.

This is achieved, according to the invention, in that the rotor isarranged eccentrically in the enclosure, in that the enclosure issymmetrical with respect to the connection line between the shaft of therotor and the point of the enclosure closest to this axis, the southpole and in that, based on an XY coordinate system placed through theaxis of rotation of the rotor and running orthogonally to and in thedirection of the axis of symmetry, and with polar coordinates (r, j)with their center in the rotor shaft and the angle j=0 lying in thedirection of the positive X-axis, the inside wall of the enclosuresatisfies the following equation:

r _((j)) ={a>>b>>/[a>> cos >>(1(j+D/2))+b>> sin >>(1(j+D/2))]}^(½)

where:

b is the shortest distance between the rotor shaft and the enclosurewall at the south pole,

a is given by the formula

a _((d,b))={[3(d/2)⁴−2b>>(d/2)>>]/[2(d/2)>>−b>>]}^(½)

where:

d is the length of the chords of the inside enclosure wall through theaxis of rotation of the rotor, thus, the radial extension of the slides,and 1 is given by the formula

1=2/D arccos ({[a>>−(a ⁴ +b ⁴ −a>>b>>)^(½)]/(a>>−b>>)}^(½))

Thus, the shape of the inside enclosure wall is completely determined bythe choice of b and d; that is, the shortest distance between rotorshaft and inside enclosure wall, on the one hand, and the radialextension of the slides, on the other, since due to the requirement ofsymmetry with respect to the Y-axis, the curve need only be fixed in onequadrant and it will be fixed in the other quadrant; the others [sic;other parameters] result immediately.

Added to the above are the boundary conditions: the horizontal profile(parallel to the X-axis) at the south pole (that at the north pole willresult automatically), the position of the inside enclosure wall at theintersection with the X axis in a spacing d, the requirement forcontinuous differentiation two times in order to design therotation-displacement motion of the slides without any jumps, monotonicincrease of r_((j)) in the fourth quadrant and always non-negativecurvature, whereby the curve is fixed.

Configurations of the invention pertain to the formation of the slidesand their guidance in the rotor or along the enclosure.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing, some sections through the enclosure or rotors areschematically represented according to the invention. Shown are:

FIG. 1, an enclosure shape with a=1.5 and b=1;

FIG. 2, an enclosure shape with a=2.0 and b=1;

FIG. 3, an enclosure shape with a=5.0 and b=1;

FIG. 4, a section through a turbine or ventilator;

FIG. 5, a section through a two-stage rotary piston internal combustionengine;

FIG. 6, an axial section through a rotary piston internal combustionengine;

FIG. 7, a section through a rotary piston internal combustion jetengine;

FIG. 8, a slide in section, plan view and side view;

FIG. 9, a spring yoke in section, plan view and side view;

FIG. 10, a rotor in section and side view;

FIG. 11, an ellipsoidal ring in plan view and side view;

FIG. 12, a rotor segment in front view and side view;

FIG. 13, a segment gasket in front view and side view;

FIG. 14, a rotor in section and side view;

FIG. 15, a rotor segment in front view and side view; and

FIG. 16, a slide in section, plan view and side view;

DETAIL DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1—3 show various constructions of enclosure shapes that can beemployed in keeping with the invention as functions of parameters a andb. The coordinate systems used, the south pole S, and the distances band d are also entered with b set to 1 in each case since the shape ofthe curve depends only on the ratio a/b, and thus also, based on therelationship above, on a/d.

As is immediately evident from FIGS. 1-3, according to the inventionenclosure shapes in the range of a/b [from] ¼ [to] 2 are certainlytechnically practicable while, for values of a/b that are considerablyhigher, strong accelerations of the slides appear when the latter aresituated in an equatorial position (parallel to the X-axis).Additionally, contact forces from the enclosure wall that press stronglyand are directed out of the slide plane are also active in thisposition, and thus do not qualify such shapes for technical utilization.

Usable ratios a/b lie between 1.0 and 2.5, preferably between 1.25 and2.0, a and b having the significance stated above.

Even for the ratios shown in FIGS. 1 and 2, and obviously also for thosein which a <1.5 or only slightly more than 2, a rotary piston machine iscreated which does not exhibit the disadvantages of previously knownmachines and, in particular, has favorable dynamic conditions for themotion of the slides in the radial direction of the rotor and also alongthe inside enclosure wall.

FIG. 4 shows a section perpendicular to the axis of rotation of aturbine or ventilator according to the invention. Slides 1 move in therotor 19 guided in oil, as is explained in detail below. In theenclosure wall 32, drawn in only schematically in all illustrations, thesuction opening 17 and the pressure opening 23 are shown schematicallyby hatching.

Use as a pump for generating a vacuum and for pumping fluids as well asfor compressing can be accomplished in an analogous but reversed manner.

FIG. 5 shows a section of a rotary piston internal combustion engineperpendicular to the axis of rotation according to the invention. Asuction opening 17 of a compressor stage is schematically drawn in theenclosure wall 32, as well as an overflow channel 18 which leads fromthe compression side of the compressor stage to the suction side of theengine stage. There is an injection nozzle 20 shown in the area of theexpansion chamber.

The slides 1 of the compressor stage are again guided in oil in therotor 19; for thermal reasons, this is not possible for the slides 21 ofthe rotor 22 in the combustion chamber.

The spent combustion gases leave the rotary piston internal combustionengine at the exhaust opening 23. FIG. 6 shows a section through theparallel rotor shafts 30, 33 of the two rotors 19, 22 of FIG. 5. Inparticular, the rounded corner shaping of the enclosure chambers can bediscerned from this figure. The bearings 29 for the rotors 19, 22 andthe gears 31 that ensure the powering of the compressor rotor 19 areshown.

FIG. 7 shows a section perpendicular to the rotor shafts of a rotarypiston jet engine. A precompressor outlet opening issues into anexpansion chamber 27 that ends in the exit nozzle 28; also evident arethe schematically drawn suction opening 17 and the overflow channel 18that leads from the precompressor stage into the expansion stage. Theslides 1 guided in the precompressor rotor 19 are preferably againguided in oil, while this is not possible for the slides in the rotor22, as they are highly stressed thermally by the combustion process.

According to the invention, FIG. 8 shows a preferred slide 1, insection, in side view and in plan view, in which grooves 3 are visibleinto which spring yokes, one of which is represented in FIG. 9, can beinserted. Oil channels 2 are provided in the slider, which, due to thecentrifugal acceleration, transport oil that is supplied in the area ofthe rotational axis outward and there lubricate and cool the slide 1 orspring yoke during its rotation along the inside enclosure wall.

FIG. 9 shows a spring yoke that can be inserted into the grooves 3 of aslide 1 and is provided with lubrication openings 5 from which thelubricating fluid can exit. The arrows indicate the direction of the(slight) elastic deformation caused by the centrifugal acceleration, bywhich deformation the seal on the inside enclosure wall is improved.

The bridges 34 between the two ends of the slide 1 are offset in theindividual slides of a rotor by at least the bridge width, so that theindividual slides are arranged to be radially movable past one another.

FIG. 10 shows a rotor for oil-lubricated slides 1 which is thus not ableto withstand high thermal stresses since otherwise carbonization of theoil would occur. Other fluids besides oil can be employed forlubrication, both oil and the other fluids being usable for cooling. Inthe case of vacuum pumps, particularly because oil contamination can notbe removed from a vacuum, the slide can be cooled and lubricated byfluids such as water.

Such a rotor 19 preferably consists of rotor segments 7 which are heldtogether with intermediate slot-like spaces by rotor sidewalls withmounting holes 11. The slides 1 slide in the spaces 12. Ellipsoidalrings 13 (FIG. 11) are inserted into grooves 8. The grooves 9accommodate segment gaskets 15 (FIG. 13); oil supply for the slides 1 orthe spring yokes 4 is accomplished through an inlet opening 10 in therotor shaft.

In FIG. 11, an ellipsoidal ring 13 is shown in a side and a plan view.The direction of pressure here is indicated by arrows. The ellipsoidalring 13 has an opening 16 for equalizing pressure and expansion. Theellipsoidal ring 13 serves to seal the slide 1 off with respect to therotor; in the illustrated embodiment, two such ellipsoidal rings areprovided on each side of the rotor for each of the slides 1, thus, fourellipsoidal rings per slide [are needed].

A rotor segment in front and side view can be seen in FIG. 12; thegrooves 8 for the ellipsoidal rings 13 or the grooves 9 for the segmentgasket 15 (FIG. 13) can also be seen. The holes 14 of the rotatorsegments 7 cooperate with the holes 11 in the lateral disc 6 and serveto assemble the lateral discs 6, 25 (FIG. 6).

In FIG. 13, a segment gasket 15 is represented in front and side view.This segment gasket 15 seals off the rotor with respect to the lateralenclosure wall and is constructed to be self-contacting.

FIG. 14 shows a rotor able to withstand high thermal stresses in anaxial section in which a combustion chamber 26 is provided in eachsegment. An individual rotor segment is shown in front and side view inFIG. 15; FIG. 16 shows an associated slide 21, which differs from slide1 in its lack of an oil supply and thus of lubrication. Here too, thebridges 34 are arranged as for slide 1 (FIG. 8).

The mode of operation of the rotary piston machine, according to theinvention, is the same as that for ordinary rotary piston machines;except for the dynamic improvements of the slide movement and of thespatial configuration of the slides which thereby becomes possible, nochange from prior art regarding operation has taken place.

What is claimed is:
 1. Rotary piston machine in which at least one rotor(19, 22) rotates in an enclosure (32), and radially movable slides (1,21) in the rotor form chambers of varying volume between the enclosureand the rotor, wherein an even number of slides is provided and mutuallyopposing slides are joined together in a rigid unit, characterized inthat the rotor is arranged eccentrically in the enclosure, in that theenclosure is symmetrical with respect to the connection line between theaxis of the rotor and the point of the enclosure closest to this axis,the south pole (S) and in that, based on an XY coordinate system placedthrough the axis of rotation of the rotor and running orthogonally toand in the direction of the axis of symmetry, and on polar coordinates(r, j) with their center in the rotor shaft and the angle j=0 lying inthe direction of the positive X-axis, the inside wall of the enclosure(32) satisfies the following equation: r _((j)) ={a>>b>>/[a>> cos>>(1(j+D/2))+b>> sin >>(1(j+D/2))]}^(½) where: b is the shortestdistance between the rotor shaft and the enclosure wall at the southpole (S), a is given by the formula a_((d,b))={[3(d/2)⁴−2b>>(d/2)>>]/[2(d/2)>>−b>>]}^(½) where: d is thelength of the chords of the inside enclosure wall through the axis ofrotation of the rotor, thus, the radial extension of the slides (1, 21),and 1 is given by the formula 1=2/D arccos ({[a>>−(a ⁴ +b ⁴−a>>b>>)^(½)]/(a>>−b>>)}^(½)).
 2. Rotary piston machine according toclaim 1, characterized in that the ratio a/b lies between 1.0 and 2.5,preferably between 1.25 and 2.0, a and b having the meaning specifiedabove.
 3. Rotary piston machine according to claim 2, characterized inthat its slides (1) have oil channels (2) running essentially radiallywhich interact with oil channels (5) in spring yokes (4) that are seatedin grooves of the slides (1), and seal off the latter against the insideenclosure wall in order thereby to achieve a reduction of the frictionbetween inside enclosure wall and slide.
 4. Rotary piston machineaccording to claim 1 characterized in that its slides (1) have oilchannels (2) running essentially radially which interact with oilchannels (5) in spring yokes (4) that are seated in grooves of theslides (1), and seal off the latter against the inside enclosure wall inorder thereby to achieve a reduction of the friction between insideenclosure wall and slide.